Virtual OP simulators of the type mentioned above are generally known. By way of example, the applicant of the present application is marketing simulators such as these. Furthermore, virtual OP simulators for training for minimal-invasive operations are known, for example, from U.S. Pat. No. 5,800,178 or U.S. Pat. No. 5,629,594.
In general, modern computer-aided simulators for carrying out virtual operations require a relatively large amount of computation power which is required, on the one hand for calculation of the virtual operation site, the soft tissue simulation and the virtual instruments, and on the other hand for driving the corresponding motor-based input unit for force reaction and force feedback, and for recording of the instrument position and other input parameters. Both the drive for the input unit for force reaction and the recording of the instrument position and other input parameters should take place in real time, in which case the frequencies for force reaction should also be significantly higher since, otherwise, the user is not provided with a realistic training sensation. In this context, real time means that the transmission frequency of the individual parameters corresponds at least to that frequency at which frames are displayed on a display of the computer-based simulator (referred to in the following text as the video frequency).
A plurality of computer systems have until now generally been used for this purpose, for example on the one hand a high-performance PC for virtual imaging and for simulation of the soft tissue, and on the other hand digital signal processors with suitable software for driving the corresponding motor systems for force reaction.
This computation complexity and the complexity associated with it for the required computers increases when instruments and their force reaction are intended to take place in a plurality of degrees of freedom, and the aim is to simulate not only the movement of the instrument but also the distal force influence of the endoscopic instrument on the tissue and vice versa (action=reaction). The complexity increases further when the aim is to simulate more than one access.
Against this background, the object of the invention is to develop a virtual OP simulator of the type mentioned initially such that the requirements for the computer power of the simulation computer unit can be reduced, with the aim of being able to move the instrument within at least four degrees of freedom.
This object is achieved by the virtual OP simulator mentioned in the introduction in that a monitoring control unit is provided, which is connected to the simulation computer unit and to the instrument input unit, with the monitoring control unit having a first interface which provides communication of parameters between the monitoring control unit and the simulation computer unit at a speed in the region of the video framing rate, and having a second interface which provides communication of parameters with the instrument input unit at a speed which is higher than, in particular a multiple of, the video framing rate, and the instrument input unit allows a total of four degrees of freedom, detects movements of the instrument within these degrees of freedom, supplies corresponding signals to the monitoring control unit and receives signals for the force feedback unit, at least some of which are generated by the simulation computer unit.
For the purposes of the present invention, the expression “parameter” means a data item (which may possibly be composed of a plurality of individual data items as well) for description of a value, for example the position of the instrument.
In other words, this means that the data records associated with one parameter are transmitted at a frequency which corresponds to the video framing rate or to a multiple of it.
The monitoring control unit makes it possible to reduce the load on the simulation computer unit since a smaller amount of data need be transmitted per unit time to the monitoring control unit. This then also results in less computation complexity for production of this data. This data essentially comprises force values which are required for production of the force reaction to the instrument.
However, the data transmission from the monitoring control unit to the instrument input unit and the force feedback unit takes place at a very much higher rate, so that it is possible to provide the user with a realistic force reaction.
In addition to this advantage of the reduced requirements on the simulation computer unit, a further advantage of the virtual OP simulator according to the invention is that the instrument can be moved in at least four degrees of freedom, in which case all of the movements can be recorded by the instrument input unit and a force reaction can be produced for each movement. The four degrees of freedom are two tilting movements (x and y directions; also referred to as pitch and yaw), a translational movement of the instrument into and out of the instrument input unit (z direction; referred to as “trans”) and a rotary movement of the instrument about its own longitudinal axis (also referred to as roll).
The virtual OP simulator thus allows considerably more realistic training than the known OP simulators.
In one preferred development, the first interface is a serial interface, in particular a USB interface.
It is thus possible to use the USB interface, which is provided as standard on a PC, for communication with the monitoring control unit. Furthermore, the transmission speed of a serial interface is sufficient to achieve the required relatively low transmission speed.
In consequence, the advantage is that the requirements for the simulation computer unit can be reduced.
In a further development, the second interface is a parallel interface
In comparison to a serial interface, this has the advantage that a considerably higher transmission speed is possible, and the complexity can be kept low by using a standardized interface such as this.
In one preferred development, the instrument is related on the proximal side to a resectoscope with optics, a resection loop and a rinsing shaft, and has an actuating element, in particular a microactuating element, which is associated with the force feedback unit and injects a force into the axial loop movement, which force simulates distal-side tissue resistance to the loop.
In other words, this means that the actuating element can be used to provide the user with realistic resistance when touching and gripping tissue during operation of the resection loop, this being the resistance which would be exerted by the resistance of the tissue that had been touched and/or gripped during a real operation.
The advantage in this case as well is that this allows a further improvement in the “realism” of the OP simulator.
In a further development, valvecocks are provided on the rinsing shaft of the instrument and are provided with sensors for recording of the valvecock movement, with the signals which are produced by the sensors being transmitted via the monitoring control unit to the simulation computer unit.
In other words, this means that the virtual OP simulator according to the invention also allows simulation of the operation of the valvecocks and of the functions associated with them. By way of example, the operation of a valvecock may cause the simulation computer unit to simulate rinsing and to display this appropriately on a monitor. Particularly during endourological interventions, spontaneous bleeding occurs very frequently and has an extremely deleterious effect on the endoscopic view. The view can be reproduced only by active rinsing.
The advantage in this case as well is that the virtual OP simulator allows even more realistic training.
In one preferred development, the electrical lines for transmission of electrical signals to and from the instrument are passed via the normally provided light connection. From there, they are carried in a manner corresponding to an optical waveguide in a flexible tube to the monitoring control unit.
In other words, this means that the electrical lines are passed into the interior via the light connection that is provided on an instrument, so that the instrument does not require any additional openings, etc.
The advantage of this measure is that the user is provided with the impression of a real instrument with an optical waveguide, since the cable routing, the weight, the lever ratios etc., correspond to the original instrument. Supplying the lines to different points would lead to the handling of the “training” instrument differing from that of the original instrument.
In one preferred development, the optics of the instrument have an associated endoscopic camera dummy, which is designed on the suspension principle.
In other words, this means that an apparatus is provided on the optics of the instrument which is related to an endoscopic camera, but without having to have any optical elements. In this context, “suspension principle” means that the camera body always points downward as a result of the force of gravity, even when the axis of the instrument is rotated (rolled). This means that the endoscopic horizon remains the same. By way of example, the applicant is marketing such original suspension cameras under the product number 22210032-3 or 22210132-3.
The advantage of this measure is that it results in a further improvement in the realism of the OP simulator.
In a further development, the camera dummy produces control signals which are supplied to the monitoring control unit and relate to specific functions of a camera, in particular focus and zoom.
This measure has the advantage that functions can additionally be simulated via the simulation computer unit which are provided by the endoscopic camera during a normal operation (these include, in particular, focusing of the image and enlarging or reducing the size of the image).
This measure also advantageously makes it possible to improve the realism of the OP simulator according to the invention further.
In one preferred development, the first interface operates at a transmission rate of the individual parameters of 16 to 60 Hz.
In other words, this means that the interface can receive and transmit 16 to 60 data records or values per second for each parameter. However, a value of 50 Hz, that is to say 50 data records or values per second and parameter, is preferable, corresponding to the normal video framing rate. If, for example, it is intended to transmit two parameters, the interface has to transmit a total of 100 data records per second (in each case 50 for each parameter).
By way of example, four discrete signals for adjustment of the force feedback for the four degrees of freedom, a data record for indicating the rotation direction of the force feedback and a data record relating to the state of the overall system are transmitted as parameters from the simulation computer unit to the monitoring control unit.
By way of example, the following data is transmitted as parameters from the monitoring control unit to the simulation computer unit: four data records with the position data (for the four degrees of freedom), eight data records from the instrument and camera, and one data record with state variables, for example the state of three switches in the camera dummy, the state of two foot-operated switches, the state of a trocar module in the instrument input unit (instrument in the trocar).
The abovementioned details relating to the parameters to be transmitted are purely by way of example and may, of course, be changed and matched to particular conditions.
The advantage of the low transmission rate according to the invention is that the simulation computer unit has to provide a relatively small amount of computation power for data transmission so that, in comparison to previous systems, more computation power is available for the actual simulation, that is to say the display on a monitor and the calculation of force reaction values. Overall, this allows conventional standard computers (PCs) to be used which normally operate with the “Windows” operating system, which is actually not suitable for real-time applications.
In one preferred development, the second interface of the monitoring control unit operates at a transmission rate of about 1000 Hz.
In other words, this means that the interface can transmit 1000 values per second to the instrument input unit and/or to the force feedback unit. The advantage is that the user can be provided with a more realistic tactile impression.
In one preferred development, the monitoring control unit is designed to receive a number of force values per second for the force feedback unit from the simulation computer unit, to calculate a multiple of this number of force values by interpolation, and to send them to the instrument input unit for the force feedback unit.
In other words, this means that the monitoring control unit uses the values supplied from the simulation computer unit to calculate a large number of intermediate values, which it transmits to the instrument input unit. These interpolated intermediate values allow the tactile feeling during operation of the instrument to be improved further.
In one preferred development, the force feedback unit has a plurality of actuating elements which are associated with the instrument input unit and interact with the instrument.
In other words, this means that a plurality of actuating elements are provided in order to be able to produce a reaction force for each possible degree of freedom of the movement of the instrument. The corresponding actuating elements are provided either in the instrument input unit which holds the instrument, or in the instrument itself.
Since a force reaction is provided for each degree of freedom, the OP simulator can be operated very realistically and allows very realistic training.
In one preferred development, the simulation computer unit sends approximately 30 nominal force values per second to the monitoring control unit, and the monitoring control unit uses these approximately 30 values to calculate a multiple (500-1000) of values, and sends them to the instrument input unit.
In practice, this setting choice has been found to be particularly advantageous in order on the one hand to keep the computation load on the simulation computer unit low and on the other hand to allow the control of the instrument to be as realistic as possible.
In one preferred development, a single instrument is provided, and the instrument input unit has a single holder for one instrument.
This measure has also been found to be particularly advantageous in practice. However, it should be mentioned that the OP simulator according to the invention can also be used with a plurality of instruments with one instrument input unit which has a plurality of holders, or with a plurality of instrument input units.
Further advantages and refinements of the invention are specified in the other dependent claims or in the description and the attached drawing.
It is self-evident that the features mentioned above and those which are still to be explained in the following text can be used not only in the respectively stated combination but also in other combinations or on their own without department from the scope of the present invention.